<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title></title>
    <!--引入Vue-->
    <script type="text/javascript" src="../js/vue.js"></script>
</head>
<body>
    <div class="root">
        姓:<input type="text" v-model="firstName"/><br/>
        名:<input type="text" v-model="lastName"/><br/>
        姓名:<span>{{fullName}}</span><br/>
    </div>
</body>

<script type="text/javascript">
  new Vue({
    el: '.root',
    data: {
      firstName: '张',
      lastName: '三',
      fullName: ''
    },
    //u1s1,这里没有计算属性方便
    /**
     * computed能完成的,watch都能完成,反之不然
     */
    watch: {
      firstName: function(newV) {
        this.fullName = newV + '-' + this.lastName
      },
      lastName: function(newV) {
        this.fullName = this.firstName + '-' + newV
      },
    }
  })
</script>
</html>
